DSpace
 

Researchspace >
General science, engineering & technology >
General science, engineering & technology >
General science, engineering & technology >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/5279

Title: Flame temperature trends in reacting vanadium and tungsten ethoxide fluid sprays during CO2-laser pyrolysis
Authors: Mwakikunga, BW
Mudau, AE
Brink, N
Willers, CJ
Keywords: Flame temperature
Laser pyrolysis
Infrared thermography
Specific heat
Enthalpy
Damping
WO3
VO2
Issue Date: Sep-2011
Publisher: Springer Verlag (Germany)
Citation: Mwakikunga, BW, Mudau, AE et al. 2011. Flame temperature trends in reacting vanadium and tungsten ethoxide fluid sprays during CO2-laser pyrolysis. Applied Physics B: Lasers and Optics, Vol 105(2011), pp 451–462
Series/Report no.: Workflow request;7463
Abstract: We observe the “invisible-to-the- naked-eye” flames of tungsten and vanadium ethoxide aerosols when ignited at moderate laser excitation (0 < Plaser< 70 W) by employing an IR thermo-graphic camera. No emission is seen in the visible range whether by the visible region cameras or by spectroscopy. Measured emissivity values for the precursor solutions – found to be 0.8 and 0.75 for tungsten and vanadium ethoxide respectively – and the spectral emissivities of their flames (in-situ) are used to calculate the temperatures at varying laser intensity and various laser wavelengths. New energy balance equations have been derived –the transient temperature one extended from Haggerty-Cannon equation and the other based on standard resonance analysis. Fitting these models to experimental data reveals that only small amounts (1.33% and 4.32% respectively) of the laser power are used in the pyrolysis of the precursor ethoxide aerosols into the desired oxide nanostructures. The low levels of specific heat capacities obtained in these sprays suggest that these are electronic heat capacities rather than lattice heat capacities; enthalpies are also obtained. Our temperature-laser power trends are in agreement with previous findings. The damping coefficients and hence the saturation intensities confirm that the vanadium containing precursor liquid is harder to dissociate into final products than the tungsten precursor as observed experimentally.
Description: Copyright: 2011 Springer. This is the post print version of the work. The definitive version is published in Applied Physics B: Lasers and Optics, Vol 105, pp 451-462
URI: http://www.springerlink.com/content/b86k54v072463h70/fulltext.pdf
http://hdl.handle.net/10204/5279
ISSN: 0946-2171
1432-0649
Appears in Collections:National Centre for nano-structured materials
Laser physics and technology
Laser materials processing
Sensor science and technology
General science, engineering & technology

Files in This Item:

File Description SizeFormat
Mwakikunga_2011.pdf708.48 kBAdobe PDFView/Open
View Statistics

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback